This invention relates to a metallurgical powder composition and a high-wear resistant article made therefrom including a cylinder liner and a valve-seat ring wherein the metallurgical powder composition is compressed and sintered after admixture with basalt powder and, if desired, admixture with carbon, lead and/or other heavy metals.
In West German Patent No. 1,121,089 there is disclosed a lubricant for cylinder liners and valve-seat rings made of sintered iron containing carbon and lead. The articles are made by briquetting, sintering and subsequent hot or cold compression. The sintered iron contains, before treatment, 0.6-0.9% carbon, 3-4% lead, 1.5-3% nickel and copper, with the remainder being iron having conventional impurities.
In some applications, for example, in the production of valve-seat rings for the exhaust valves of motor vehicles, it is necessary that the material of the article provides a high-heat resistant property in addition to requisite strength properties. U.S. Pat. No. 3,471,343 discloses valve-seat rings having increased resistance to heating for exhaust valves of motor vehicles. The valve-seat rings are manufactured by compressing, sintering and subsequently compacting a powder mixture cntaining 0.8-1.5% graphite, 1.0-4% lead, 0.5-5% nickel, 1.2-1.8% molybdenum and 9.6-14.4% cobalt, with the remainder being iron. It is also known in the powder metallurgical art to produce valve-seat rings having a high resistance to heat by a method using metal powder containing iron, 0.5-1% carbon, 0.7-1.5% lead, 1.0-2% nickel, cobalt and 1.0-2% molybdenum. In the method, 0.5-1% carbon and 0.7-1.5% lead are added to a pulverized prealloyed metal containing 1.0-2% nickel, 6.0-7% cobalt and 1.0-2% molybdenum, the remainder being iron and conventional impurities in steel. The mixture is then briquetted, sintered and compacted when hot or cold and heat-treated if required. The addition of lead in the aforementioned material composition improves the operational characteristics of the valve-seat ring. The lead functions as a lubricant.
West German Patent Specification No. 2,155,765 discloses a valve-seat material for an internal combustion engine wherein the material is comprised of a matrix made up of an iron-based alloy containing a dispersed constituent of lead, a lead compound or glass. For example, the valve-seat material can have a matrix comprised of an iron-based alloy in which 0.5-30% by weight chromium, 0.1-3% by weight carbon, 0.3-10% by weight lead and up to 10% by weight glass are dispersed. As before, lead and low-melting point silicate glass are added to improve the lubricating properties of the valve-seat material. The lead and glass constituents in the valve-seat material flow onto the sliding surface of the valve seat where they function as a lubricant.